Scale up in ImageDecoder based on API level

Bug: 74061412
Bug: 73893665
Test: Manual, I5669a97c70d726826c5c00bc1413c2f97d95d88c

ImageDecoder typically does not scale a Bitmap up to handle density.
This saves memory, and we already handle the density by scaling at
draw time. But some apps rely on the size of the Bitmap without taking
density into account. For backwards compatibility, on apps that are
built for a pre-P version of Android, scale up in ImageDecoder.

Change-Id: I9991d1286e386b47fc57bcfbf0c6652beb1a53ef